HUBBLE-SPACE-TELESCOPE OBSERVATIONS OF 2 DYNAMICALLY YOUNG ELLIPTIC GALAXIES

High-resolution images of the candidate dynamically young ellipticals NGC 1700 and NGC 3610 have been obtained with the WFPC2 of the Hubble Space Telescope. NGC 1700 contains approximately a dozen dust clouds a rranged in a chaotic distribution near the center of the galaxy, sugge stive of a merger or accretion event. NGC 3610 contains a remarkably t wisted stellar disk within 2.7 '' (0.4 kpc for H-0 = 75) of the center , but no apparent dust features. The smooth, symmetric appearance of t his disk and the lack of correlation with the color image suggest that it is a relaxed stellar component, possibly a disk twisted by differe ntial precession. Its relevance to a past interaction remains unclear since the feature appears to be unique among ellipticals observed so f ar. A search for intermediate-age globular clusters formed during merg er or accretion events reveals a population of clusters in NGC 3610 wh ich are similar to 0.7 mag brighter in V, similar to 0.2 mag redder in V-I, and more centrally located than a typical old, metal-poor popula tion. Simulations using Bruzual-Charlot (1996, in preparation) cluster evolution models suggest that the colors and magnitudes of these clus ters are consistent with an age of 4 Gyr (assuming near-solar metallic ity). However, spectroscopic measurements of the cluster metallicities will be needed to confirm this age estimate. In the case of NGC 1700 few if any new globular clusters seem to have formed during the accret ion event that produced the loops and shells of this galaxy. Combining the present results with previous HST observations of other merger re mnants shows generally good agreement between age estimates based on p hotometric, spectroscopic, and/or kinematic observations of the remnan ts, and age estimates based on the colors and luminosities of young an d intermediate-age star clusters. (C) 1997 American Astronomical Socie ty.